We propose a randomized, placebo-controlled, double-blind study evaluating the efficacy of an ACE-inhibitor (perindopril) or a beta blocker (bisoprolol) for the prevention of LV remodeling among women with early breast cancer scheduled for chemotherapy and one year of trastuzumab. Participants will undergo cardiac MRI at baseline and 3 and 12 months, replacing the usual MUGA, as well as a post-treatment cardiac MRI at 24 months to evaluate long-term effect.